In this video I show a way to manipulate the foot to escape Knee on Belly.
While it is being shown from Knee on Belly please keep in mind that this relationship works from a lot of different places. I've had a good bit of success pulling the foot in between the legs for a long time, primarily when my partner/opponent tries to hide their foot from the outside Single or when I try to grab the ankle. When they try to pivot the foot away it becomes easily accessible.